Well, it would seem that my garage is totally the wrong environment for Vacuum casting.

In the summer when I first got my kit, temperatures were 25oc with 90%+ humidity

Winter has set in now so it will be really difficult to keep my garage above 15oc while I'm in there. Plus with all the rain we have been getting in the UK, I'm pulling 2-5 litres of water out of the air each night with my dehumidifier!

No wonder I get foaming resin and trouble with curing.

I do have a halogen cooking pot that I bought for curing minis sculpted with Fimo, I will pop some resin in there at 30oc or so while it cures and see what happens

RageofAchilles wrote:Well, it would seem that my garage is totally the wrong environment for Vacuum casting.

Wow that's an understatement!

How is it that your humidity was so high? I didn't think the UK had high humidity?

Is it safe to assume that inside your house is a much more stable environment? If so I would suggest doing some tests casting inside the house (make sure your significant other isn't home at the time ). The fumes from just a couple of mixes of polyurethane are going to be minimal and I certainly wouldn't be concerned about long term effects.

mangozac wrote:How is it that your humidity was so high? I didn't think the UK had high humidity?

Our summer weather comes from the gulf of Mexico on the gulf stream. The same weather in winter is just rain, rain and more rain so there is always water in the air no matter what. Add to that, I live about 200yards from the sea on the south coast

It could be worth me trying some indoor casting as you suggest, i'll have to be sneaky about it lol

I am also on the south coast of the UK (Portsmouth) and have had some of the problems you are exhibiting but nothing like as bad. My current workshop has a leak in the roof above the casting table and I'm still putting out saleable casts. S-C305 and various silicones.

And yeah it is extreme. I have been resin casting for about 8 years now and white metal casting for 12 years before that, just for myself. I only encountered the problems seen in the pic when using the Vacuum chamber...A problem that does seem to be more pronounced when I use a pigment in the resin. Also the parts I make are quite large, which dosen't seem to help. I did just get some perfect casts out of a new mould without using the chamber, or adding pigment to the resin. So there is hope I think

horizon wrote:So actually you two could meet up and could try to work out the problem together it's it keeps persistent.

While the advice I've been getting here is very helpful. I certainly wouldn't impose myself on another forum member like that .

It's certain that the environment of my garage , the low power of my Vacuum pump, the incompatibility of my silicon moulds and the lack of a pressure chamber are all factors in the problems I've been having casting larger kit parts. It's just going to take time and considerable investment of funds to sort it out.

Fleafa wrote:What power is the vacuum pump? That and no pressure would explain the fine bubbles to me. I have no experience with the anti-foaming additive.

It's only a 1.5cfm . It was included in a starter kit with a 7.5ltr Vacuum chamber. I know I should be using something like a 6cfm pump but at £200-£300 it's just out of the question. I have a clear idea in my mind of how to sort things out now, I just can't afford to do it lol

Not certain if this thread is still active, but just stumbled on it, and thought Id add a note to this particular section.

I had unexpected bubble and brittle issues with a new batch of resin, in spite of both vacuum and pressurizing. Turns out So-Strong pigments also have a limited shelf life. The bubbles where caused by moisture introduced by the pigments. Even in the small amounts of pigment used, the moisture content reeked havoc.